Masonry Arching

[pmblair]

In the old 6 minutes solutions there is a problem with 12' 8" height masonry wall by 20 ft long masonry wall with door opening 6'8" by 4' wide. The lintel is made of steel angles. There is 700 # point load directly above the lintel in the middle of the door opening.

The solution says to ignore the 700# point load and half the masonry load because the wall will arch because there is equal length of masonry on each side of the opening ie... there is 4' or more on each side of the door. They also ignore half the weight of the masonry above the door.

I have a serious issue with this problem. Would you really ignore say a 10 kip point load only 6 ft above a door opening under the assumption the wall would arch? This seams ridiculous that any one wouldn't design that lintel for that load and ignore the top 3 ft of the self weight of the masonry......

 

[bootlegend]

I wouldn't do it in practice. But on the exam they will probably expect us to do exactly that.

 

[dastuff]

It was probably ignored because a majority of the force will distribute away from the opening. If it changed to only having 2' of headroom i would definitely treat it as a beam.

Although I agree with bootlegend that in practice i'd probably conservatively assume some of the load does act on it (maybe take 4'/12' or 33% distribution onto the angle/masonry).